首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2892篇
  免费   303篇
  国内免费   12篇
耳鼻咽喉   16篇
儿科学   66篇
妇产科学   69篇
基础医学   498篇
口腔科学   70篇
临床医学   304篇
内科学   509篇
皮肤病学   94篇
神经病学   510篇
特种医学   107篇
外科学   302篇
综合类   11篇
一般理论   2篇
预防医学   207篇
眼科学   54篇
药学   178篇
中国医学   7篇
肿瘤学   203篇
  2024年   3篇
  2023年   32篇
  2022年   60篇
  2021年   84篇
  2020年   78篇
  2019年   101篇
  2018年   105篇
  2017年   100篇
  2016年   113篇
  2015年   119篇
  2014年   168篇
  2013年   160篇
  2012年   275篇
  2011年   266篇
  2010年   135篇
  2009年   141篇
  2008年   175篇
  2007年   175篇
  2006年   169篇
  2005年   135篇
  2004年   126篇
  2003年   127篇
  2002年   95篇
  2001年   27篇
  2000年   22篇
  1999年   27篇
  1998年   19篇
  1997年   15篇
  1996年   13篇
  1995年   12篇
  1994年   13篇
  1993年   7篇
  1992年   8篇
  1991年   8篇
  1990年   9篇
  1989年   12篇
  1988年   7篇
  1987年   6篇
  1986年   4篇
  1985年   8篇
  1982年   3篇
  1981年   3篇
  1980年   3篇
  1979年   5篇
  1978年   4篇
  1977年   3篇
  1975年   3篇
  1974年   3篇
  1969年   7篇
  1932年   2篇
排序方式: 共有3207条查询结果,搜索用时 15 毫秒
101.
Maintaining and improving fitness are associated with a lower risk of premature death from cardiovascular disease. Patients with schizophrenia are known to exercise less and have poorer health behaviors than average. Physical fitness and physiological regulation during exercise tasks have not been investigated to date among patients with schizophrenia. We studied autonomic modulation in a stepwise exhaustion protocol in 23 patients with schizophrenia and in matched controls, using spirometry and lactate diagnostics. Parameters of physical capacity were determined at the aerobic, anaerobic, and vagal thresholds (VT), as well as for peak output. VT was correlated with psychopathology, as assessed by the Positive and Negative Syndrome Scale, with the inflammatory markers IL-1β, IL-6, and TNF-α and with peak output. The MANOVA for heart and breathing rates, as well as for vagal modulation and complexity behavior of heart rate, indicated a profound lack of vagal modulation at all intensity levels, even after the covariate carbon monoxide concentration was introduced as a measure of smoking behavior. Significantly decreased physical capacity was demonstrated at the aerobic, anaerobic, and VT in patients. After the exercise task, reduced vagal modulation in patients correlated negatively with positive symptoms and with levels of IL-6 and TNF-α. This study shows decreased physical capacity in patients with schizophrenia. Upcoming intervention studies need to take into account the autonomic imbalance, which might predispose patients to arrhythmias during exercise. Results of inflammatory parameters are suggestive of a reduced activity of the anti-inflammatory cholinergic pathway in patients, leading to a pro-inflammatory state.Key words: heart rate, physical exercise, respiration, schizophrenia, vagal threshold, cardiac death, inflammation, physical fitness  相似文献   
102.
103.
Deficiency of the major constituent of central nervous system (CNS) myelin, proteolipid protein (PLP), causes axonal pathology in spastic paraplegia type‐2 patients and in Plp1null‐mice but is compatible with almost normal myelination. These observations led us to speculate that PLP's role in myelination may be partly compensated for by other tetraspan proteins. Here, we demonstrate that the abundance of the structurally related tetraspanin‐2 (TSPAN2) is highly increased in CNS myelin of Plp1null‐mice. Unexpectedly, Tspan2null‐mutant mice generated by homologous recombination in embryonic stem cells displayed low‐grade activation of astrocytes and microglia in white matter tracts while they were fully myelinated and showed no signs of axonal degeneration. To determine overlapping functions of TSPAN2 and PLP, Tspan2null*Plp1null double‐mutant mice were generated. Strikingly, the activation of astrocytes and microglia was strongly enhanced in Tspan2null*Plp1null double‐mutants compared with either single‐mutant, but the levels of dysmyelination and axonal degeneration were not increased. In this model, glial activation is thus unlikely to be caused by axonal pathology, and vice versa does not potentiate axonal degeneration. Our results support the concept that multiple myelin proteins have distinct roles in the long‐term preservation of a healthy CNS, rather than in myelination per se. GLIA 2013;61:1832–1847  相似文献   
104.
105.
106.
107.
Journal of Autism and Developmental Disorders - Individuals with Autism Spectrum Disorder (ASD) and the Broad Autism Phenotype (BAP) are more likely than individuals with typical development (TD)...  相似文献   
108.
Koch  Julia  Willemsen  Kira  Dogan  Imis  Rolke  Roman  Schulz  Jörg B.  Schiefer  Johannes  Reetz  Kathrin  Maier  Andrea 《Journal of neurology》2022,269(2):923-932
Journal of Neurology - Studies have reported autonomic impairment in patients with idiopathic REM sleep behaviour disorder (iRBD), which is considered a prodromal stage of alpha-synucleinopathies....  相似文献   
109.
Although antibiotics are known to affect the intracellular growth of Chlamydia pneumoniae in acute infections, their efficacy in therapy for chronic infections, including atherosclerosis, remains debatable. Human monocyte-derived macrophages (MDM) obtained from monocytes of healthy donors were infected with C. pneumoniae AR-39 and treated with levofloxacin (8 microg/mL) immediately after infection (0 hours) or 24 hours after infection. Levofloxacin treatment at 24 hours, but not at 0 hours, resulted in a significant decrease in the number of C. pneumoniae inclusions within the MDM (p < 0.05). Also decreased were concentrations of proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-8 in the extracellular medium (p < 0.01). Viable counts in titrations remained similar to those in untreated controls. In summary, levofloxacin administered to MDM at serum-attainable levels 24 hours after C. pneumoniae infection significantly decreased inclusion counts and proinflammatory cytokine production, but did not eliminate the C. pneumoniae infection.  相似文献   
110.
Improving the hemocompatibility of artificial implants by micro structuring their surfaces has shown promising results, but the mechanisms which lead to this improvement are not yet understood. Therefore, we built a test setup for real‐time visualization of platelet interaction with a plain and two micro structured surfaces. The micro structures, defined by the distance of the plain surface area between the structures, were chosen to be 3 and 30 μm, representing a positive and a negative effect on the hemocompatibility. The main part of the test setup was a flow chamber containing films of low density polyethylene (LDPE) with the differently structured surfaces. For different wall shear stresses, no considerable differences were observed in the platelet‐surface interaction for all surface types. Whereas, major differences in flow behavior were observed when comparing the surfaces to each other. The platelets “rolled” along the smooth surface, being in constant contact with the surface material. Although the platelets “rolled” over the surface with small structures as well, they were only in contact with the tips of the structure and therefore had less surface contact with the foreign material. The increased distance and height of the structures of the last surface led to a trapping of platelets between the structures. This resulted in a longer contact time with the foreign material as well as a larger contact area, which both increase the risk of platelet activation, adhesion, and finally clotting. Our results showed the mechanisms which lead to these effects and thus revealed why micro structuring of surfaces impacts the hemocompatibility. Furthermore, we established a test setup which can be used for future investigations on the platelet‐structure interactions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号